Lydia had been playing Halo 3 with her brother nearly all day, only taking a break to receive Batman and make sure he understood that he couldn't leave her room or Phil would start having sneezing fits. By two, Phil retreated to the store after getting his ass handed to him several times in a row and her mother was no where to be found.
So, when she buzzed them up it was just her and the Halo 3 screen was paused, controller abandoned on the couch. She opened the door wide and stepped aside for them, her smile warm.